Giuseppe Panerai, son of Guido Panerai, joined his father in Guido Panerai & Figlio in 1925. Italian Wikipedia describes him as an inventive engineer who patented many devices and credits him with Radiomir, a luminous radium paste sealed in cells or transparent tubes for instrument dials, sights and gun reticles. In 1936 the First Submarine Group of the Royal Italian Navy asked the firm for a diver's wristwatch readable in deep, murky water; the Radiomir watch, with a 47 mm cushion case and a Rolex crown and movement, was supplied from 1938 and worn by frogmen of the Decima Flottiglia MAS during the Second World War. After the war radium was replaced with Luminor, a tritium-based compound, and the patented crown-protecting bridge became the brand's trademark. The firm also supplied the Egyptian Navy, with the Egiziano of 1956, and the Israeli Navy. English Wikipedia names "Giuseppe Panerai", with Rolex's Hans Wilsdorf, as a driving force behind the first professional diving watches. He died in 1972. Casadi has not verified his date of birth.